As mobile technology improves, mobile devices have become smaller and more powerful. The wireless networks they connect to have improved as well. These improvements mean that mobile devices can now be used for many functions beyond simple voice calling. For example, these devices can be used to send email, browse the Internet, and send instant messages. Mobile devices have also expanded to add functionality previously found only in dedicated media player devices, including playing multimedia items such as music files and video files. This functionality can be used to play multimedia items stored on the mobile device or streamed from remote servers accessed through the wireless network. The expanded capabilities of modern mobile devices also include improvements in input and display technologies. For example, many modern mobile devices include large, high-resolution displays that are capable of displaying more complicated user interfaces than were possible on earlier, smaller screens. Many mobile devices now include touch-sensitive screens that allow more intuitive control of the device's user interface. However, interface technologies have changed only slowly to accommodate these additional capabilities.